The immune system is the body's primary defense against diseases caused by invading organisms, such as bacteria, viruses or parasites, as well as diseases caused by abnormal growth of the body's own tissues (i.e., cancerous tumors). Normally, the immune system is able to distinguish the body's normal tissues, or self, from foreign or cancerous tissue, or non-self. The loss of recognition of a particular tissue as self, and the subsequent immune response directed against that tissue, typically results in an "autoimmune response" that often has serious clinical consequences.
One specific example of such an autoimmune disease is multiple sclerosis (MS), a progressive disease of the central nervous system (CNS) in which patches of myelin (the protective covering of nerve fibers) in the brain and spinal cord are destroyed by the body's own immune system. This destruction leads to scarring and damage to the underlying nerve fibers, and may manifest itself in a variety of symptoms, depending on the parts of the brain and spinal cord that are affected. Spinal cord damage may result in tingling or numbness, as well as a heavy and/or weak feeling in the extremities. Damage in the brain may result in muscle weakness, fatigue, unsteady gain, numbness, slurred speech, impaired vision, vertigo and the like.
Current therapies for multiple sclerosis include corticosteroid drugs (to alleviate the symptoms of acute episodes), as well as other biomolecules. In particular, beta-interferon (IFN.beta.) has been tested and approved by the U.S. Food and Drug Administration (FDA) as an MS therapy. Unfortunately, the presently-used therapies suffer from a range of problems. The drugs are often toxic at the doses required for a maximal therapeutic effect. Further, the body may become desensitized to the drug such that higher (and more toxic) doses are required to maintain even a minimal therapeutic effect.
The present invention provides a method of treatment for autoimmune diseases, such as MS, that does not have the toxic side effects associated with currently-used therapies.